Method for producing a joining unit and joining unit

Abstract

The invention relates to a method for producing a joining unit (10, 40, 40 '), in particular of an energy store unit (30) of an energy store or of an electrolysis device, in which a first component (12, 44, 44') having a first connecting section (20, 44a, 44a ') made of a metallic material is provided, and in which a second component (24, 24a, 24b, 42) having a second connecting section (20, 44a, 44a') made of a metallic material is provided, the second component has a second connection section (24, 24a, 24b, 48) made of an electrically insulating material. In this case, the first connecting section (20, 44a, 44a ') and the second connecting section (24, 24a, 24b, 48) are arranged in contact with each other and are bonded to each other in a cohesive manner by means of a thermal bonding method, and at least the second connecting section (24, 24a, 24b, 48) is heated at least in some regions according to the thermal bonding method.

Description

Technical Field

[0001] The invention relates to a method for producing a joining unit, in particular an energy storage unit for example for a motor vehicle energy storage unit, wherein a first component is provided, which has a first connecting section consisting of a metallic material, wherein a second component is provided, which has a second connecting section consisting of an electrically insulating material. The invention also relates to a joining unit, in particular a joining unit for an energy storage unit of a motor vehicle energy storage unit. Background Art

[0002] In particular in the case of designs for motor vehicle energy storage devices, but also in other applications, in order to join different components, in particular to join metal components to electrically insulating components (e.g. plastic components), depending on the application, either methods are used in which the plastic components are joined to the metal components in an injection molding process, or adhesives and / or sealing materials are used. The adhesive or sealing material then has to be applied in a separate process step and then cured, for which purpose a curing unit such as an oven is used in a subsequent process, for example. Overall, this type of joining process is very cost-intensive and complex.

[0003] DE 100 25 207A1 describes a fuel cell, which consists of a stack of membrane electrode units arranged in succession using flat sides, the membrane electrode units are separated from each other by bipolar plates, and wherein monopolar plates are respectively arranged as end plates before the first membrane electrode unit and after the last membrane electrode unit. Distribution and collection channels for the supply and discharge of fuel, oxidant and cooling medium for the fuel cell are provided in the stack. In this case, the membrane electrode units, bipolar plates and end plates are respectively surrounded by plastic frames, which can be attached to the individual units or plates by injection molding. These plastic frames are connected to each other in a sealing manner by welding or bonding.

[0004] Furthermore, DE 10 2007 007 986 A1 describes an energy storage device for electrical energy, which in particular comprises a housing for at least one energy storage cell installed and fastened in the housing, the energy storage cell consisting of at least one electrode pair surrounded on all sides by a flexible housing, wherein the flexible housing is sealed on at least one side of the energy storage cell by a seam, thereby producing a frame adjoining the electrode pair. The energy storage cell is fastened in the housing by clamping at least one frame between housing modules. This makes it possible to dispense with the usual folding of the weld seam. Summary of the invention

[0005] The object of the present invention is to provide a method and a joining unit, in particular for an energy storage unit, which allow production which is as efficient as possible.

[0006] This object is achieved by a method and a joining unit according to the respective independent claims. Advantageous embodiments of the invention are the subject matter of the dependent claims, the description and the drawings.

[0007] In the method according to the invention for producing a joining unit, in particular for producing an energy storage unit for an energy storage device of a motor vehicle, a first component is provided, which has a first connecting section composed of a metallic material, and a second component is provided, which has a second connecting section composed of an electrically insulating material. In this case, the first connecting section and the second connecting section are arranged in contact with each other and are joined to each other in a materially bonded manner by means of a thermal joining method, according to which at least the second connecting section is heated at least partially.

[0008] Here, the present invention is based on the following recognition: it is possible to provide a very stable, firm and material-locked connection between a component made of an electrically insulating material, such as a plastic component and a metal component, by at least partially melting the component made of an electrically insulating material. This melting can be provided by the described thermal joining method, according to which at least a part of the second connecting section composed of an electrically insulating material is at least locally heated. As explained in more detail later, for example, this heating can be provided by a heating device to heat the second connecting section, but alternatively, heating can also be provided by radiation, for example by means of a laser, but heating can also be provided by mirror welding, friction welding, hybrid welding, etc. Thus, according to the design, local, point-shaped or linear heating of the second connecting section is achieved, and a very narrow and fine joining contour is produced, and a large-area melting is achieved and a large-area joining connection with the first connecting section is established accordingly. Thus, a variety of different possible uses are advantageously provided for the described method. In addition, another recognition on which the present invention is based is that the material-locked joining connection provided in this way is not only extremely stable mechanically, but also fluid-tight. Thus, by this thermal joining method, not only can a stable connection be established between the two connection sections, but also a sealed joint connection can be established between the two connection sections if desired. Compared with, for example, using an adhesive, at least partially heating at least the second connection section is significantly simpler and faster. In particular, a significantly finer joint connection can also be provided in a difficult-to-reach area, which is impossible or can only be realized in a very complex manner, for example, by a traditional joint method. In addition, for this thermal joining method, no additional material, such as an adhesive, is required. Thus, additional components, weight and materials can be saved. In addition, the joint connection can also be realized extremely in a space-saving manner and in the smallest space, because additional materials do not have to be applied to the joint pair. That is, a particularly effective joint method and a manufacturing method for a joint unit for manufacturing, for example, an accumulator unit for a motor vehicle accumulator can be provided. Accordingly, additional adhesives or sealing materials can be omitted or at least significantly reduced in quantity. The investment and continuous cost for the hardening unit and the space, personnel and energy requirements required for this can be reduced or omitted. The melted electrically insulating material, for example a plastic material, hardens significantly faster than an additionally applied adhesive or sealant. This makes it possible, for example, to further process the joined parts earlier and with less effort. Accordingly, the risk of a displacement of the positions of the two joined parts relative to one another is also lower. By means of the circumferential connecting seam, in addition to the positional fixation, a medium-tight connection can also be established between the two parts. In other words, additional functionality, namely a sealing function, can be integrated by means of this joining method.

[0009] In the automotive sector and / or in the production of energy storage devices such as batteries or fuel cells, for example for motor vehicles, but also in the production of stationary energy storage devices such as stationary fuel cells or stationary batteries, in particular high-voltage batteries, these findings bring great advantages in particular when producing joint components, which are also referred to as joint units here. Nevertheless, other applications are also conceivable, such as the use of the production method in the production of electrolyzers or electrolyzer components, or also in the vehicle assembly of motor vehicles, in particular in the production of bodywork. Although the preferred embodiments of the invention explained in more detail below mainly relate to energy storage applications, the concepts and features explained here can also be applied similarly to other application cases.

[0010] Here, a component or member including at least two mutually engaged individual parts (i.e., a first member and a second member) is referred to as a joining unit. The joining unit may also be referred to as a joined unit, a joined member, a joining member, a joined component, a joined member, a joining component, etc.

[0011] For example, the joining unit can be a joining unit or a component of an energy storage unit of the energy storage unit. For example, the energy storage unit can be an electrochemical or chemical energy storage unit. For example, the energy storage unit can be configured as a fuel cell and / or as a battery, in particular a high-voltage battery, for example, for a motor vehicle, or as a fixed energy storage unit. Here, the first component of the energy storage unit having a first connecting section composed of a metallic material does not necessarily have to be composed entirely of a metallic material, but can still be composed entirely of a metallic material. The same also applies to the second component. In particular, the second component also does not have to be composed of an electrically insulating material in its entirety, but at least has a second connecting section composed entirely of an electrically insulating material.

[0012] The electrically insulating material is at least partially fusible and has a melting point lower than the metal material constituting the first connecting section. Preferably, the electrically insulating material is plastic, or at least includes plastic, but the electrically insulating material can also be other electrically insulating materials, such as natural rubber or wax. For example, the second component can be a plastic component. The electrically insulating material can also be a plastic containing a filler material, such as a fiber-reinforced plastic, such as a plastic containing embedded fibers (such as fibers formed by glass, carbon, metal), etc. The filler material (the filler material can also be formed by glass, carbon, metal, etc.) can also be provided in a form other than fibers, such as powder, plate, etc. Here, the filler material does not necessarily have to be fusible or have a melting point lower than the metal material constituting the first connecting section. Here, as a plastic component of the electrically insulating material, in principle, any plastic can also be considered. It is particularly advantageous to use thermoplastics, such as polyethylene naphthalate (PEN), which is very advantageous when the second connecting section is configured as a frame of an MEA (membrane electrode unit), for example. However, any other plastic can also be considered.

[0013] In principle, any metallic material is also conceivable as the metallic material.

[0014] The method can therefore be used in a very large number of applications in which a metal component is to be joined, for example, to a plastic component in a mechanically stable and optionally also fluid-tight manner.

[0015] Therefore, after the first connecting section and the second connecting section are arranged in contact with each other, there is a physical contact between the first connecting section and the second connecting section. That is, there is a contact surface between the first connecting section and the second connecting section. After the thermal joining method is carried out, a material-locked joint connection is produced in this contact area, that is, via this contact surface.

[0016] Here, a thermal joining method is defined as a joining method which, when carried out, results in the second connecting section being at least partially heated, preferably at least partially heated on the contact surface mentioned above. The heating is designed to cause the electrically insulating material, for example plastic, of the second connecting section to melt at least partially, in particular in the contact region with the first connecting section, that is to say, preferably at least partially on the contact surface mentioned above. In other words, the part of the electrically insulating material of the second connecting section that is in direct contact with the first connecting section melts, whereby a material-locked connection with the first connecting section is produced after the melted electrically insulating material solidifies or hardens again.

[0017] After the application of the thermal bonding method, the second connection section is in a solid state. In other words, the electrically insulating material of the second connection section is solid in this state and is not soft or has partially melted or liquefied. That is, the first connection section and the second connection section are arranged together in a solid state. Subsequently, the contact surface of the second connection section with the first connection section is partially melted by applying the thermal bonding method, according to which at least this part of the second connection section is locally heated).

[0018] Depending on how the geometry of the joint connection is to be designed, the geometry of the local heating of the second connection section can be designed accordingly according to the thermal joining method. In other words, a joint connection between the two connection sections is ultimately produced in a locally heated area. If, in other words, a joint connection is not to be established in a certain contact area between the two connection sections, this can be achieved in that the second connection section is also not heated in this area. As a result, free areas can also be provided in a targeted manner in the joint connection and the joint connection can be designed flexibly and according to requirements in terms of geometry.

[0019] In an advantageous design of the present invention, a cell separator is manufactured as a joining unit of the energy storage unit for being arranged between two cells of the energy storage unit configured as a battery module. Therefore, such a cell separator (which is often also referred to as a cell separator) can be arranged between two cells of the battery module. Here, such a cell separator is used to separate the cells spatially from each other, to prevent the spread of flames in the event of a fire in the battery, and in part also to thermally insulate the cells from each other, and furthermore to compensate for swelling. That is, the cell separator can be configured to be elastically deformable in at least one direction, wherein, in a state where the cell separator is installed in the battery module, this direction can correspond, for example, to the stacking direction of the cell stack of the battery module, with a plurality of cells of the battery module being arranged side by side in the stacking direction.

[0020] In addition, the battery cell can be a lithium-ion battery cell. The battery cell is preferably designed as a prismatic battery cell and / or a soft-pack battery cell. That is, in a top view, the battery cell has a substantially rectangular geometry in the stacking direction.

[0021] According to another very advantageous design of the present invention, a cell separation unit having a wall made of a metal material surrounding an inner space is provided as a first component, wherein at least a portion of the surrounding edge region of the cell separation unit is a first connection section. For example, the wall can be designed as a flexible shell. In particular, the wall can be provided by one or two thin metal foils that are joined to each other. The two metal foils can be joined to each other in a surrounding manner in the edge region. The inner space surrounded by the wall can be filled with a gas, such as air. As a result, the cell separation device or the cell separation unit included in the cell separation device is designed in the form of an air-filled air cushion or an air-filled air bag, and can be elastically deformed accordingly relative to the pressure effect. Therefore, when the cell expands, the cell separation unit can be compressed accordingly, and when the cell shrinks, the cell separation unit can expand again accordingly. Here, the two metal foils can be joined to each other in the edge region by welding.

[0022] In order to withstand the higher pressures in the battery modules, the metal foils should be welded correspondingly firmly, and the fine welds produced should be able to withstand the high forces from the battery cells as described above.

[0023] Therefore, another very advantageous design of the present invention is that as the second component, at least one first frame part made of an electrically insulating material, in particular plastic, is provided, the first frame part being at least a part of the second connecting section, in particular wherein the second component additionally has a second frame part, the second frame part also being a part of the second connecting section, wherein the first frame part and the second frame part are arranged at the edge region of the cell separation unit in such a way that the edge region of the cell separation unit is located between the first frame part and the second frame part. By means of the first frame part and in particular also by means of the second frame part, two functions can be provided at the same time: on the one hand, electrical insulation of the edge side of the cell separation device can be advantageously provided. In particular the edge region of the cell separation device forms part of the outer side of the battery module. Typically, the poles of the cell are also arranged on this outer side. Thus, by means of the insulation of the edge side provided by at least one first frame part and in particular also by means of the second frame part, it is advantageously possible to provide just a reliable electrical insulation of the cell poles and the cell connector. On the other hand, a further additional function can be provided by the first frame part, which is or will be joined to the cell separation unit according to a thermal joining method, in that an incompressible spacer can be provided in the edge region of the cell separation device, for example in the form of an incompressible frame surrounding the cell separation device. As a result, a certain minimum distance between the cells can be provided in the edge region and the minimum distance is defined by the thickness of the cell separation device in this edge region. This prevents, for example, excessive compression of the cells during assembly of the battery module or the cell stack and at the same time also flattens the cell separation unit. Advantageously, the cells can thus be kept at a defined minimum distance from each other by the cell separation device. A particularly great advantage of the first frame part and especially also the second frame part is that the weld seam described above, or in general the joining connection between two metal foils for providing the cell separation unit, can be stabilized and supported by the plastic frame. Thus, in particular when installed in the battery module, pressure is applied to the weld or joint connection between the metal foils via the additional plastic frame, and the metal foil is additionally sealed and stabilized in its surrounding edge region by this compression in the weld region. As a result, the possibility or risk of the separation element not being sealed in the edge region, more precisely in the region of the joint connection between the metal foils, can be significantly reduced, and the resulting loss of function of the cell separation element can be prevented. In addition, by the described thermal bonding method, the frame part and the cell separation unit can be connected to form a unit in the edge region, in particular by material locking. As a result, due to this inseparable connection, it is easier to handle the component and ensure that the reliable function of the electrical insulation is ensured at the necessary locations. As a result, slippage or the like is also excluded.Furthermore, the handling and positioning of the components during production processes, for example during the subsequent assembly of the module, is simplified.

[0024] According to another advantageous design of the present invention, the first frame part and the second frame part respectively extend beyond a portion of the edge region after being arranged on the edge region, wherein in the thermal joining method, the edges of the first frame part and the second frame part extending beyond the edge region are additionally joined to each other, in particular welded to each other.

[0025] Advantageously, the two frame parts can therefore be welded together in the extended edge region by the same joining method, so that a frame unit can be provided which surrounds or encloses the cell separation unit at the edge. Thus, when viewed in cross section, a U-shaped geometry is obtained by the two mutually joined frame parts. As a result, the outer edges of the cell separation unit are surrounded by the plastic frame, more precisely by the mutually welded parts of the two frame parts. In addition, a particularly reliable and safe edge insulation of the cell separation unit can be provided.

[0026] The frame or the first frame part and the second frame part can, for example, have a rectangular geometry. In this case, the first frame part and the second frame part surround the edge area of ​​the cell separation unit along a closed contour. However, it is also conceivable that the frame is configured to provide the frame only on two opposite sides or opposite edges of the cell separation unit. In this case, it can also be provided that the frame is not provided by two mutually joined frame parts, but by a first frame part, which is, for example, arranged around (U-shaped around or enclosed) a first edge of the cell separation unit and is subsequently joined to this edge on both sides using a thermal joining method. The same approach can be repeated for the second frame part on the opposite side edges of the cell separation unit.

[0027] In this case, the frame parts—both the first and the second frame parts—can generally be of very thin design and be provided, for example, in the form of a plastic film or a film made of another electrically insulating material.

[0028] In another advantageous embodiment of the present invention, the cell separation unit is arranged between two cells, so that the minimum distance between a first cell edge region of the first cell and a second cell edge region of the second cell is defined by the thickness of the cell separation unit in the region of the joined frame parts. As a result, incompressible spacers can be provided in the edge regions of the cells at the same time by the joined frame parts.

[0029] For certain applications, the surrounding frame provided at least by the first frame part can also be partially recessed / recessed.

[0030] In another advantageous embodiment of the present invention, the joining unit or component of the fuel cell stack, in particular the joining unit or component of the unit cell (Einheitszelle) of the fuel cell stack presented as an accumulator unit, is manufactured as a joining unit of the accumulator unit. In conventional fuel cells, a medium-tight space must usually be established. Here, a seal that assumes this function in a compressed state is usually used, or an inseparable connection can also be established between the paired parts to be joined by applying an additional adhesive or by welding a metal single plate, or a combination of the above methods is used. Here, the so-called MEA (Membran Elektroden Assembly, membrane electrode assembly), that is, the membrane electrode unit is often connected to a single plate or a bipolar plate. Within the scope of the present invention, the monopolar plate is referred to as a single plate. Here, the MEA is mostly constructed in such a way that the CCM (Catalyst coated membrane, catalyst coated membrane), that is, the catalyst-coated membrane of the reaction area is integrated into a plastic frame, for example, made of PEN. Advantageously, this makes it possible to join such an MEA to an adjacent metal plate, such as a bipolar plate or a single plate, by the thermal joining process already described above and to simultaneously seal it relative to the plate. This also enables significant advantages in terms of time saving, material saving and efficiency to be achieved during the production of such a fuel cell unit.

[0031] Therefore, another very advantageous embodiment of the present invention is that a metal plate, in particular a bipolar plate or a single plate, is provided as the first component, wherein the first connection section is provided by at least a part of the edge region of the plate. Furthermore, a membrane electrode unit, i.e. the MEA described above, is provided as the second component, wherein the second connection section is a membrane electrode unit frame surrounding the reaction area of ​​the membrane electrode unit, in particular wherein a fluid seal is provided between the first connection section and the second connection section by a thermal bonding connection between the first connection section and the second connection section.

[0032] Advantageously, the described thermal joining method makes it possible, for example, to dispense with the need for pre-injection molding of a plastic frame around such a plate (e.g. a bipolar plate or a single plate). Such a plate can then be simply arranged on the corresponding MEA and subsequently the MEA can be partially melted in the edge region, more precisely in the region of the MEA frame made of electrically insulating material, in particular the plastic frame of the MEA, by heating, thereby producing a sealed joining connection to the plate.

[0033] Here, the unit cell of the fuel cell has a membrane electrode unit, which can also be referred to as a membrane electrode assembly, and additionally or with a bipolar plate or alternatively with two single plates arranged on opposite sides of the membrane electrode unit. In principle, the bipolar plate can have a structure similar to or equivalent to the structure of the two single plates. A fuel cell or a fuel cell stack can be formed by stacking a plurality of such unit cells. Thus, between two MEAs, there are two single plates or a bipolar plate, respectively. The stack can be defined at the end side by a single plate. A free space that can be flowed through, for example in the form of a channel, can be constructed between the single plates or within the bipolar plate. Accordingly, two adjacent single plates can also be sealed to each other. For this purpose, the joining methods known in the prior art can be used. If a corresponding unit cell includes an MEA and a bipolar plate, in order to form a fuel cell, the individual unit cells can also be joined to each other by a thermal joining method, that is, by partially melting the plastic of the relevant MEA plastic frame located between each two bipolar plates. Here, MEAs and bipolar plates can be stacked one after the other and after each additional layer a thermal joining method is carried out as described to connect, ie, the plastic frame of the MEA is connected to the adjacent bipolar plate in a materially bonded manner.

[0034] Combinations of the described thermal joining methods with conventional joining methods such as adhesive bonding or adhesive sealing are also conceivable for constructing a fuel cell stack.

[0035] The plate, that is to say, a single plate and / or a bipolar plate, can usually be constructed very thinly, for example, in the form of a foil. In addition, a medium interface can be integrated in the plate and in the corresponding frame member of the MEA as a through opening or notch. The medium can be provided to supply and discharge the medium to the reaction area through the medium interface, as well as the supply and discharge of cooling water. However, the medium supply and discharge can also be realized by an external channel connected to the fuel cell stack by a flange. Here, a joint connection between the MEA and the adjacent metal plate can be implemented according to the situation and needs. For example, the joint connection can be provided by a closed surrounding joint profile. In addition, this profile or other profiles such as surrounding the medium interface can also be provided with corresponding interruptions to realize a through area for the medium. By using this thermal bonding method in this fuel cell (especially for the manufacture of fuel cell units), an additional sealing effect can be generated between the metal plate and the MEA by a melted frame material, that is, a melted electrical insulating material of the MEA frame. Advantageously, additional sealing materials can be omitted and the sealing function can be simply realized. In addition, the risk of short circuit at the alignment position can be reduced. By forming the assembly structure of the MEA and the bipolar plate or single plate in advance, the number of individual components to be stacked is reduced. The welded bipolar plates or single plates provide the MEA with stability. In addition, the quality during the stacking process can be ensured more easily, in particular by making the measurement technology more technically simpler. For example, only one sensor is required for a metal edge to be measured. By fastening two components to each other in a sealing manner, that is, fastening the MEA to at least one metal plate, a new "module" is created that simplifies the stacking process, handling and logistics chain.

[0036] In another advantageous embodiment of the invention, the components of the stationary energy storage device are produced as a joined unit. The stationary energy storage device can also be designed as a battery as described above, in particular a high-voltage battery, or as a fuel cell as also described above.

[0037] In another advantageous design of the present invention, a part of the electrolysis device is manufactured as a junction unit. For example, the structure of the electrolysis device is similar to that of a fuel cell. The electrolysis device includes a plurality of electrolysis chambers arranged in a row, and the required redox reaction occurs in the electrolysis chamber by inputting electrical energy. Accordingly, such an electrolysis chamber can be a junction unit. Such an electrolysis chamber can also have a diaphragm with a surrounding frame, and plates arranged on one side or both sides of the electrolysis chamber, such as two single plates or a bipolar plate. Here, the plate can be made of a metal material, and the frame of the diaphragm unit is made of an electrically insulating material, such as plastic. In particular, similar to the description of the fuel cell, a plurality of these junction units can be stacked to provide an electrolysis device.

[0038] In another advantageous embodiment of the invention, the motor vehicle component is produced as a joined unit during vehicle assembly, in particular during bodywork production. The described method also offers great advantages during bodywork production. Accordingly, the joined unit can be a component of the body of such a vehicle. For example, to produce such a bodywork component, a metal component as a first component can be joined to a film made of an electrically insulating material, for example a plastic film, as a second component.

[0039] In another advantageous design of the present invention, thermal bonding and heating are achieved by means of a heating device, which is in physical contact with the first connection section and / or the second connection section, especially with the first connection section. This approach is particularly suitable when a larger connection connection is to be provided. By physically arranging such a heating device on the corresponding connection section, the connection section can also be stabilized. The heating device can also be used as a support at the same time, and is used, for example, to provide additional pressure loading during the joining process. At this time, it is preferred that the heating device is arranged at the first connection section, rather than the second connection section. The heat of the heating device can be directly transferred to the second connection section made of an electrically insulating material through the first metal connection section, and cause the electrically insulating material to melt in a locally positioned manner. The heating device is also prevented from sticking to the second connection section itself. In addition, the electrically insulating material of the second connection section, in particular, melts in the contact area with the first connection section, or first melts in the contact area, or melts the strongest in the contact area, and thus melts just at the location where the material-locked connection is to be established, that is, at the contact surface with the first connection section.

[0040] According to another advantageous embodiment, the thermal joining is carried out by means of a laser, by means of which the radiation of the laser is at least partially heated to the first connecting section and / or the second connecting section. For example, the laser or the radiation provided by the laser can be directed directly to the second connecting section to heat it. This enables the second connecting section to be melted in a targeted manner. However, preferably, the laser beam is not directed directly to the second connecting section, but is also preferably directed to the first connecting section. The local heating of the metal of the first connecting section then directly leads to the local heating of the corresponding contact area of ​​the second connecting section and its melting.

[0041] The use of a laser avoids direct physical contact with the second connecting section and in particular also with the first connecting section and prevents adhesion even in the event of direct action on the second connecting section.

[0042] Furthermore, the use of lasers makes it possible to provide particularly fine and thin joint contours. Using the example of a cell separator element, this also makes it possible, for example, to simultaneously produce a joint connection between the frame part and the cell separator unit and between two metal foils that form the cell separator unit or that form components of the cell separator unit when producing a joint connection between the frame part and the cell separator unit.

[0043] That is, generally speaking, a heat conduction method is recommended as a thermal joining method, which heats the surface to be joined by direct contact and melts the thermal insulation material in shape (e.g., mirror welding), and then connects the thermal insulation material to the joining partner, for example, by applying additional pressure. It is also possible to input heat by laser beam. For example, the laser beam heats the metal at the position to be joined with the electrically insulating material in the following manner, so that the electrically insulating material melts there and connects to the metal. The connection can be optimized by applying additional pressure. Thus, a medium-tight connection can also be established in the case of a circumferential weld. Other heat conduction methods, such as induction methods, are also possible.

[0044] Furthermore, the invention relates to a joining unit, in particular a joining unit for an energy storage unit of a motor vehicle energy storage unit, wherein the joining unit is produced by means of the method according to the invention or one of its embodiments.

[0045] In particular, the invention also relates to a joining unit, for example a joining unit for an energy storage unit of a motor vehicle energy storage unit, wherein the joining unit comprises: a first component having a first connecting section formed of a metallic material; and a second component having a second connecting section formed of an electrically insulating material, for example plastic. The first connecting section and the second connecting section are arranged in contact with each other and are joined to each other in a materially bonded manner via at least a melted and resolidified region of the second connecting section.

[0046] The advantages described for the method according to the invention and its embodiments apply in the same manner to the joining unit according to the invention.

[0047] The invention also includes a development of the joining unit according to the invention, which has the features already described in conjunction with the development of the method according to the invention. For this reason, the corresponding development of the joining unit according to the invention will not be described in detail here.

[0048] The present invention also includes an energy storage unit and / or an energy storage device having a coupling unit according to the invention or one of its embodiments, and a motor vehicle having a coupling unit according to the invention or one of its embodiments, wherein the motor vehicle has an energy storage device according to the invention or one of its embodiments.

[0049] The motor vehicle according to the invention is preferably designed as a car, in particular a passenger car or a commercial vehicle, or as a bus or a motorcycle.

[0050] According to another embodiment, the energy storage unit can also be a stationary energy storage unit.

[0051] Furthermore, the invention relates to an electrolysis device having a joining unit according to the invention or one of its embodiments.

[0052] The present invention also includes combinations of features of the embodiments described. Therefore, the present invention also includes implementations which each have a combination of features of a plurality of the embodiments described, as long as these embodiments are not described as mutually exclusive. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The following describes an embodiment of the present invention.

[0054] Figure 1 A schematic diagram showing a single step for manufacturing a cell separation device according to an embodiment of the present invention;

[0055] Figure 2 A schematic cross-sectional view of a portion of a cell separation device between two cells manufactured according to an embodiment of the present invention is shown;

[0056] Figure 3 A schematic diagram showing a plurality of cell separation devices during a manufacturing process according to another embodiment of the present invention;

[0057] Figure 4 A schematic perspective view of a fuel cell unit with an MEA bonded to a bipolar plate by a fusion process according to one embodiment of the present invention is shown;

[0058] Figure 5 A schematic diagram showing individual manufacturing steps for manufacturing a fuel cell unit with a bipolar plate and an MEA according to one embodiment of the present invention; and

[0059] Figure 6 A schematic diagram of individual process steps for producing a fuel cell unit with an MEA and two individual plates according to another exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0060] The embodiments described below are preferred embodiments of the present invention. In the embodiments, the described components of the embodiments are the individual features of the present invention that can be regarded as independent of each other, and these features also improve the present invention independently of each other. Therefore, the present disclosure should also include feature combinations that are different from the illustrated embodiment feature combinations. In addition, the embodiments may also be supplemented by other features in the already described features of the present invention.

[0061] In the figures, the same reference numerals respectively denote elements with the same function.

[0062] Figure 1A schematic diagram of a single process step for manufacturing a cell separation device 10 according to an embodiment of the present invention is shown. Here, the cell separation device 10 is an example of a joining unit, for example, a joining unit of an energy storage unit for a motor vehicle energy storage unit. Thus, in this example, the energy storage unit is a battery module, and the energy storage unit is, for example, a high-voltage battery for a motor vehicle. The energy storage unit can also be a stationary energy storage unit. Here, the cell separation device 10 includes a cell separation unit 12. The cell separation unit in turn includes a shell 14 that surrounds the interior space. The shell 14 is metal and is provided in this example by two mutually joined foils 16a, 16b. For this purpose, the foils 16a, 16b can be pre-pressed to form a convex three-dimensional structure. Here, the foils are joined to each other in an encircling manner in the edge region 20 by corresponding joining contours 22, for example, welded to each other. Here, the encircling weld seam 22 can be composed of individual weld seam sections, in which the weld seam is implemented to extend in a straight line and intersect. In this case, in the first process step S10, two metal foils 16a, 16b are joined to form a cell separation unit 12. In the subsequent second process step S12, two frame parts are provided, namely, a first frame part 24a and a second frame part 24b. The two frame parts are respectively configured in a rectangular shape. Here, the length and width of the corresponding frame parts 24a, 24b can basically correspond to the length and width of the cell separation unit 12. However, preferably, the frame parts 24a, 24b are implemented so that they are slightly longer and wider than the cell separation unit 12, so that the frame parts 24a, 24b at least partially extend beyond the edge area 20 and extend beyond the edge area at least on one side of the cell separation unit 12, and in this example extend beyond the edge area on all sides. Here, the frame parts 24a, 24b are made of an electrically insulating material, which is a plastic in this example and the example explained below, but in principle can also be other electrically insulating, fusible materials. Now, the frame parts are arranged in the edge area 20 of the cell separation unit 12. If the frame parts are correctly arranged on the cell separation unit 12 in the edge region 20, in particular in such a way that the weld seam 22 is covered, in particular on both sides, as shown in the subsequent step S14, the two frame parts 24a, 24b are joined to the edge region 20 of the cell separation unit 12 and at the same time the two frame parts are connected to each other in a materially bonded manner in the protruding edge region. The joining is carried out in this case according to a thermal joining method, which is designed to melt the frame parts 24a, 24b at least in some areas. In this case, pressure can be applied to each frame part 24a, 24b in the direction of the edge region 20 of the cell separation unit 12 located between the frame parts. The partially melted plastic is connected to the metal material in the edge region 20 at the contact surface with the edge region 20 of the cell separation unit 12. As a result, an extremely stable connection is produced between the frame parts 24a, 24b and the cell separation unit 12.In addition, the two frame parts 24a, 24b can be melted at the same time in the edge area where the frame parts extend. As a result, the metal edge 18 surrounding the cell separation unit 12 is completely covered by the plastic of the frame parts 24a, 24b. As a result, the surrounding metal edge 18 of the cell separation unit 12 can also be implemented to be reliably electrically insulated to the outside. Subsequently, the cell separation device 10 produced in this way can be arranged between two cells of a battery module or in order to manufacture a battery module.

[0063] Here, Figure 2 A schematic cross-sectional view of a portion of such a cell separator 10 is shown in a state in which it is arranged between two cells 28 of a battery module 30. For example, the cell 28 can be designed as a prismatic cell. The cell wall adjacent to the cell separator 10 is indicated here by the reference numeral 28a. In this case, Figure 2 The outer shell 14 of the cell separation unit 12 is shown again, which surrounds or encloses the inner space 32 of the cell separation unit 12. Here, the inner space 32 can be designed to be filled with gas, especially air. As a result, a certain flexibility and also elastic deformability are given to the cell separation unit 12 in the central area. The outer shell 14 is also especially as Figure 1 The embodiment is described and comprises two foils 16a, 16b, which are joined to each other by a welded connection 22 along a weld contour 22. The edge region of the joined foils 16a, 16b is again indicated by the reference numeral 20. This edge region 20 is now bordered by a plastic frame 24. In this case, the frame 24 completely covers the metal edge 18 of the housing 14. Optionally, the frame 24 can also mainly consist of two films 24a, 24b. Here, the frame 24 can be joined to the edge region 20 of the cell separation unit 12 as described above, i.e. by a thermal joining process, in which a part of the plastic of the frame 24 is melted and thus connected to the metal material of the cell separation unit 12 in a material-locked manner in the edge region 20, optionally under the application of additional pressure. At this time, the heating of the plastic of the frame 24 is carried out in a manner that is only limited in time. If the plastic material is sufficiently melted, the heating can be terminated. If the frame 24 is pressed against the corresponding surface of the edge region 20 of the cell separation unit 12, the melted plastic material of the frame 24 solidifies again and is thus very stably connected to the metal in the edge region 20 of the cell separation unit 12. Figure 2 It can be clearly seen in FIG. 2 that the protruding edges of the corresponding films 24 a, 24 b are also welded to each other, so that the edge 18 is also covered with plastic.

[0064] In principle, it is also conceivable that the frame is designed not to completely surround the edge region 20 of the cell separation unit 12. It is also conceivable that such a frame 24 is provided only on opposite edge regions 20, for example above and below the cell separation unit 12, or on the left and right of the cell separation unit 12. For example, the frame 24 can also be provided only by a plastic component, for example by a film made of plastic surrounding the edge region 20, which is fused to the metal in the edge region 20 of the cell separation unit 12 by heating.

[0065] Therefore, in addition to the surrounding frame 24, it is also conceivable to apply it on selected edges of the cell separation unit 12. That is, for example, it is recommended to adopt a continuously applied process in mass production. For example, if such a frame element 24 is to be applied to a certain edge of the cell separation unit 12, it can be implemented for this edge in such a way that two plastic bands or plastic strips are applied to the upper and lower sides of the sheet metal forming the cell separation element 12 in the corresponding edge area. That is, the two plastic bands or plastic strips are arranged on opposite sides in the edge area of ​​the cell separation element 12. For example, the plastic bands or plastic strips are connected to the sheet metal or are also additionally connected to each other by means of a pressing roller. For this purpose, the plastic bands or plastic strips can extend beyond the edge of the sheet metal on the edge side. This then leads to a U-shaped wrapping (Umlappung) of the sheet metal edge after joining.

[0066] In addition, by simultaneously providing a plurality of cell separation units 12 arranged side by side and in particular not yet separated from each other with corresponding plastic bands or plastic strips (i.e., as in Figure 3 This approach can be used for mass production (as shown in the examples shown in and described below).

[0067] Figure 3 A schematic diagram of a plurality of cell separation devices 10 during a processing method according to another embodiment of the invention is shown. In this case, the cell separation device 10 can be implemented as described above. In the present example, a plurality of identical cell separation devices 10 can be manufactured simultaneously. To this end, for example, the cell separation unit 12 can be formed from a common first metal foil 16a' and a common second metal foil 16b' in that the two metal foils are joined together in the corresponding edge region 20, for example by means of laser welding. Immediately thereafter or also in the same step, the frame parts 24a, 24b, which are first implemented as a one-piece integral frame, can be placed on both sides of the corresponding cell separation unit 12, as in Figure 3 , and subsequently the frame part is joined to the cell separating unit 12 along the circumferential contour by means of a laser 34 and a laser beam 36 provided by the laser by laser welding.

[0068] Alternatively, instead of a frame, a plastic band or strip can also be placed on both sides on the edge, so that the plastic band or strip extends across the edges of multiple cell separation units. In addition, joining can usually also be carried out by means of the above-mentioned pressing rollers, which - in particular - run on the plastic band placed on the edge, so that the two edges of the sheet metal forming the cell separation unit 12 are located between such a pair of rollers, and the upper and lower plastic strips are also located between the roller pairs, and the edges of the two sheet metals of the cell separation unit 12 are located between the upper and lower plastic strips. As an alternative to joining by means of pressing rollers, laser welding or other welding methods can also be used again here.

[0069] Subsequently, the cell separation devices 10 manufactured in this way can be separated from each other, for example, by a separation method, such as cutting them apart.

[0070] Figure 4 A schematic diagram of another example of a joining unit 40 for an energy storage unit for example a motor vehicle energy storage unit or for a stationary energy storage unit is shown. In this example, the joining unit 40 is implemented as a fuel cell unit 40. The fuel cell unit includes a so-called MEA 42, i.e., a membrane electrode unit 42, which is arranged on a bipolar plate 44 and joined to the bipolar plate. Here, the MEA 42 includes a reaction area 46 arranged in the center and a plastic frame 48 surrounding the reaction area. In the plastic frame 48 and correspondingly in the bipolar plate 44 arranged below, a notch 50 is arranged, through which a medium interface is provided. The medium interface is used for medium supply and discharge, in particular for cooling water and also for the medium supply and discharge of the reactants or initial materials of the reaction, i.e., for the medium supply and discharge of the reaction products. In general, at this time, the MEA 42 and such a bipolar plate 44 can be constructed as known from the prior art. Usually, such an MEA 42 is joined to the bipolar plate 44 using an adhesive and / or a sealant. Advantageously, a particularly fluid-tight connection between the MEA 42 and the bipolar plate 44 can now also be established using the already described thermal joining method. In this case, the joining connection is also achieved by at least partially melting a portion of the plastic of the frame 48 of the MEA 42. As a result, in particular in the edge region of the bipolar plate or along the desired joining contour, the molten plastic itself is correspondingly connected to the bipolar plate 44 located below it. Here, the joining connection provided by the molten plastic is indicated by the reference numeral 52. The joining connection is arranged circumferentially in the edge region 48a of the frame, as well as in the edge region 44a of the bipolar plate 44 located below, and in this example also surrounds the notch 50 for the medium interface. Here, the joining connection 52 can also be implemented locally with interruptions, for example, to enable, for example, a medium supply and / or discharge in the gap between the MEA 42 and the bipolar plate 44.

[0071] exist Figure 5 An exemplary manufacturing method for manufacturing such a fuel cell unit 40 is shown in FIG. Figure 5 The individual process steps during the production of such a fuel cell unit 40 are shown again, which in this example also includes an MEA 42 and a bipolar plate 44, or is formed by the MEA 42 and the bipolar plate 44. In this case, in a first step S16, the MEA 42 and the bipolar plate 44 are first provided. In this example, the bipolar plate 44 is made entirely of metal. The frame 48 of the MEA 42 is made entirely of plastic and, as described, surrounds the reaction area 46, which is implemented in a rectangular shape in this example. The bipolar plate 44 can also be divided into a reaction area 44b and a surrounding frame area 44a, so that when stacking and positioning as performed in step S18, the edge area 44a of the bipolar plate 44 is placed in direct contact on the edge area 48 of the MEA 42, and the corresponding reaction areas 44b, 46 are also stacked on each other in the correct position. Then, in step S20, the assembly is positioned on a support element 54, which is also a heating device 56. In step S22, the heating device is heated accordingly and heat is transferred to the bipolar plate 44, and the bipolar plate in turn transfers heat to the MEA 42 located above, thereby locally melting the plastic in the edge region 48 of the MEA. During the heating as performed in step S22, a force F, in particular a pressing force, can be applied to the assembly formed by the MEA 42 and the bipolar plate 44 in addition, that is, simultaneously or in time overlap. As a result, the corresponding edge regions 44b, 46 are pressed together. As a result, the melted plastic of the frame 48 of the MEA 42 is stably and materially connected to the metal material of the frame region 44a of the bipolar plate 44.

[0072] In step S24, the heat supply by the heating device 56 is first terminated, and the application of pressure is also terminated. Furthermore, for example, after the molten plastic has solidified again, the heating device 56 can be removed again, and the pressing structure 58, which can be placed on the upper side on the frame area 48 of the MEA 42 to provide pressure loading by the force F, can also be removed. Finally, in step S24, the fuel cell unit 40 is provided, wherein the MEA 42 is now joined to the bipolar plate 44 by the molten and resolidified plastic 52.

[0073] In this case, the fuel cell unit 40 may be composed not only of the MEA 42 and the bipolar plate 44, but may alternatively also be composed of the MEA 42 and two individual plates 44', as in Figure 6 It is schematically shown in FIG.

[0074] Here, especially Figure 6The individual process steps for producing a fuel cell unit 40' according to another exemplary embodiment of the invention are shown again, the fuel cell unit 40' now being formed by an MEA 42 and two single plates 44'. Here, the MEA 42 can be constructed as described above and positioned between the two single plates 44' to provide the fuel cell unit 40'. The reference numeral 50' denotes a recess in the single plate 44 for the medium interface. The production process for the fuel cell unit 40' can be implemented completely in the same manner as in the embodiment of the present invention. Figure 5 The above is similar, and therefore only briefly explained below: In step S16', first provide two single plates 44' and MEA 42. Single plate 44' can also have a central reaction area 44b' and an edge area 44a'. In step S18', single plate 44' and MEA 42 are stacked and arranged in the correct position, so that plate 44 is in direct contact with MEA 42, especially the corresponding edge areas 44a' and 48 are in direct contact. In step S20', the assembly is placed on a support 54, which is also configured as a heating device. In addition, immediately in step S22', a pressure support 58 is placed on the upper single plate 44' on the other side of the assembly. In addition, in this example, the pressure support 58 is now also implemented as a heating device 56'. In step S22', two heating devices 56, 56' are activated, and specifically, the single plate 44' and the MEA 42 are heated at least partially in the edge area 48 by the heating device. Furthermore, a pressure F is again simultaneously applied to the assembly, so that the MEA 42 is pressed between the individual sheets 44' at least in the corresponding edge region 48. The heating is then stopped, and the pressure F can also be terminated after the molten plastic of the frame region 48 of the MEA 42 has hardened or solidified again. The heating device 56, 56' can then be removed and the joined fuel cell unit 40' is provided in step S24'.

[0075] The melting of the plastic in the edge region 48 of the MEA is achieved by heat conduction, in particular via the single plate 44' or via the above-described bipolar plate 44. Instead of a large-area heating device, only the edge region 44a' of the single plate 44' or the edge region 44a of the bipolar plate 44 can be heated locally in a targeted manner to achieve targeted and subsequent local melting of the plastic of the frame 48 of the MEA 42. This can be provided by a special geometric shape of the heating device 56 or alternatively also by laser welding.

[0076] In summary, the examples show how the invention provides a method for joining components for the production of batteries, fuel cells and electrolyzers and in particular provides for the welding of plastics onto metal surfaces for achieving performance.

Claims

1. A method for producing a joining unit (10, 40, 40'), in particular an energy storage unit (30) for an energy storage device of a motor vehicle, - providing a first component (12, 44, 44') having a first connecting section (20, 44a, 44a') formed of a metallic material; - providing a second component (24, 24a, 24b, 42) having a second connecting section (24, 24a, 24b, 48) formed of an electrically insulating material; It is characterized in that A first connecting section (20, 44a, 44a') and a second connecting section (24, 24a, 24b, 48) are arranged in contact with each other, and the first connecting section and the second connecting section are joined to each other in a material-locking manner by means of a thermal joining method, according to which at least the second connecting section (24, 24a, 24b, 48) is at least partially heated.

2. The method according to claim 1, characterized in that A cell separator (10) of an energy storage unit (30) is produced as a joining unit (10, 40, 40') for being arranged between two cells (28) of an energy storage unit (30) configured as a battery module (30).

3. The method according to claim 2, characterized in that - providing a cell separation unit (12) as a first component (12), the cell separation unit having a wall (14) made of a metal material and surrounding an inner space (32), wherein at least a portion of the surrounding edge region (20) of the cell separation unit (12) is a first connecting section (20); - at least one first frame member (24, 24a, 24b) made of an electrically insulating material, in particular plastic, is provided as a second component (24, 24a, 24b), the first frame member being at least a part of a second connecting section (24, 24a, 24b), in particular wherein the second component (24, 24a, 24b) additionally has a second frame member (24, 24b, 24a), the second frame member being also a part of the second connecting section (24, 24a, 24b), wherein the first frame member (24, 24a, 24b) and the second frame member (24, 24b, 24a) are arranged at the edge region of the cell separation unit (12) such that the edge region of the cell separation unit (12) is located between the first frame member and the second frame member (24, 24a, 24b).

4. The method according to claim 3, characterized in that After being arranged at the portion of the edge region, the first frame part (24, 24a, 24b) and the second frame part (24, 24b, 24a) protrude beyond the edge region (20), wherein in the thermal joining method, the edges of the first frame part and the second frame part (24, 24a, 24b) that protrude beyond the edge region (20) are additionally joined to each other.

5. The method according to any one of claims 2 to 4, characterized in that A cell separator (10) is arranged between two cell cells (28), so that a minimum distance between a first cell edge region of a first cell (28) and a second cell edge region of a second cell (28) is defined by the thickness of the cell separator (10) in the region of the joined frame members (24, 24a, 24b).

6. The method according to claim 1, characterized in that As a combined unit (40, 40') of an energy storage unit, a combined unit (40, 40') of a fuel cell stack is produced, in particular a unit cell (40, 40') of a fuel cell stack, which is an energy storage unit.

7. The method according to claim 6, characterized in that - providing a metal plate (44, 44'), in particular a bipolar plate (44) or a single plate (44') as the first component (44, 44'), wherein the first connecting section (44a, 44a') is provided by at least a part of an edge region (44a, 44a') of the plate (44, 44'); - A membrane electrode unit (42) is provided as a second component (42), wherein the second connecting section (48) is a frame (48) of the membrane electrode unit (42), which surrounds a reaction region (46) of the membrane electrode unit (42), in particular wherein a fluid seal (52) is provided between the first connecting section (44a, 44a') and the second connecting section (48) by a thermal bonding connection (52) between the first connecting section and the second connecting section (48).

8. The method according to any one of the preceding claims, characterized in that As a joining unit (44, 44'), a joining unit of an electrolysis device or a stationary energy storage device (30) is produced, or a joining unit of a motor vehicle is produced during the assembly of the motor vehicle.

9. The method according to any one of the preceding claims, characterized in that Thermal bonding is performed by means of a heating device (56, 56'), which is brought into physical contact with the first connecting section (20, 44a, 44a') and / or the second connecting section (24, 24a, 24b, 48), in particular the first connecting section (20, 44a, 44a'), and heats the same.

10. The method according to any one of the preceding claims, characterized in that Thermal joining is performed by means of a laser (34), wherein the first connecting section (20, 44a, 44a') and / or the second connecting section (24, 24a, 24b, 48) are heated at least locally by means of radiation (36) of the laser.

11. A joining unit (10, 40, 40'), in particular an energy storage unit (30) for an energy storage unit of a motor vehicle, wherein: The joining unit (10, 40, 40') is produced by means of a method according to any of the preceding claims.

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